| Ionogel is a novel quasi solid-state polymer electrolyte which retains intrinsic properties of ionic liquids and mechanical features of solid-state structural.Compared with traditional liquid electrolytes and solid-state polymer electrolytes,ionogel possess unique characteristics such as safety,nonflammability,wide temperature window,high ionic conductivity,excellent processability and flexible.Thus,ionogel has been widely applied in electronic devices such as lithium-ion batteries,supercapacitors,fuel cells and flexible sensors.However,most of current ionogel are fabricated by synthetic/man-made polymers,which are needed to be solved urgently because of their disadvantages such as environmental pollution,high cost,hardly degradability and non-biocompatibility.Therefore,considering the sustainable development,it is necessary to design and prepare ionogel with the properties of biodegradability and environmentally friendly.In this paper,we prepared a novel bio-based ionogel by chemical cross-linking reaction based on natural polymers,such as cellulose,chitosan and alginic acid,and ionic liquids as solvents and electrolytes.The gelation mechanism,the crosslinked structure,rheological properties,electrical conductivity,mechanical properties,self-healing properties and applications of ionogel in flexible electronic devices have been comprehensively characterized.The results are shown as follows:?1?A new type of chemically cross-linked ionogel based on natural chitosan and cellulose with good self-healability has been designed via Schiff base reaction.The rheological and dynamic mechanical analysis tests revealed that the as-prepared ionogel exhibited excellent thermo-mechanical stability even when the temperature was as high as150°C,and also showed good frost resistance,and still could maintain excellent flexibility even when the temperature was as low as-20°C.More importantly,the ionogel showed superior room temperature ionic conductivity?up to 2.1 mS/cm?and retained high electrical performance over a wide temperature range from-50°C to 120°C.Additionally,the ionogel was used as electrolytes for preparing flexible supercapacitors and showed good performance under high temperature and harsh mechanical conditions.Such ionogel based on natural polymers with robust mechanical properties,high ionic conductivity,self-healability,and wide working temperature will be very useful for next-generation sustainable electrochemical devices.?2?Chemically cross-linked bio-based ionogel with good self-healability based on natural alginic acid was prepared via chemically modifying and cross-linking reaction.The rheological and compression tests revealed that the ionogel possess high storage modulus?4×104 Pa?and compression modulus?3.14 MPa?which increases with increasing the content of alginic acid and crosslinker.In addition,the obtained ionogel still could maintain gel structure undestroyed even at a high temperature of 150 oC.Electrochemical tests revealed that the ionogel show high room temperature ionic conductivity(10-3 S/cm)while maintaining certain mechanical properties.More importantly,the ionogel exhibited excellent self-healability and self-healing effects.?3?A new type of high stretchable ionogel based on poly?ionic liquid??PIL?was synthesized by in situ photopolymerization in ionic liquids.The rheological tests revealed that the ionogel possess high modulus and show excellent thermo-mechanical stability.The dynamic mechanical analysis and tensile tests showed that the ionogel exhibit excellent mechanical properties,flexibility and fatigue resistance and could be stretched with 50 cycles under a fixed strain.Furthermore,the ionogel could maintain flexibility at a wide temperature range from-40°C to 200°C,showing excellent high and low temperature tolerance.Additionally,the obtained iongoel showed high room temperature ionic conductivity?up to2.8 mS/cm?and exhibit high ionic conductivity range from 10-1 to 10-2 at a wide temperature range from-40°C to 200°C.More importantly,the ionogel was used to prepare flexible sensors and showed good sensing performance,which could detect bending deformation and tensile deformation accurately even at high or low temperature. |
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